Alexander niedringhaus



UNITED STATES I ATENT FFICE.

ALEXANDER NIEDRINGHAUS, OF ST. LOUIS, MISSOURI, ASSIGNOR TO THE I ST.LOUIS STAMPING COMPANY, OFSAME PLACE.

MANUFACTURE OF ENAMELED WARE.

SPECIFICATION forming part of Letters Patent No. 568,366, datedSeptember 29, 1896. Application filed March 16, 1896. Serial No.583,440- (No specimens.)

To aZZ whom it may concern.-

Be it known that I, ALEXANDER NIEDRING- HAUS, a citizen of the UnitedStates, residing at the city of St. Louis, State of Missouri, haveinvented a certain new and useful Improvement in the Manufacture ofEnameled Ware, of which the following is a full, clear, and exactdescription, such as will enable others skilled in the art to which theinvention apper- IO tain-s to make and use the same.

This invention relates to a new and useful improvement in themanufacture of enameled ware; and it consists, essentially, in themethod of treating the base or that part which is to be enameled.

Heretofore in the manufacture of enameled ware iron has generally beenused as a base. Steel has been used to a greater or less extent for somewares, but with the result generally that pinholes, flecks, and chipsoccur to such an extent as to constitute a serious objection to its use,destroying the beauty and impairing the usefulness of the enameled ware.Pinholes, as they are called, appear irregularly over the enameledsurface and are the result of the development of a gas or gases beneaththe enamel coating during the fusion of the glaze, forming bubbleswhich, bursting, expose the black metal beneath. Flecks, as

0 they are called, also appear irregularly over the enameled surface,but are apparently produced by difierent or modified causes from thatascribed to pinholes. These flecks, or scale -like chips, differ indepth and size.

3 5 Some of them extend down to and expose the surface of the base,while others are more shallow and show the dark color of the glaze nearthe base. In many instances the enamel is not entirely flocked off, butis loosely at- 0 tached, appearing white Where the rupture of the fleckextends beneath the surface of the enamel. Moreover, it is known thatthese fieckings occur after the ware has been removed from the muflie,and it may be some 5 timebefore theyappear. Chips or chippings, as theyare called, are generally found at corners of the ware and expose thesurface of the base to a considerable extent. This is supposed to be theresult of insufficient attachment of the enamel to the base, aggravatedby the strain of gases in some cases, causing it to flake or chip off inlarge pieces and expose the base.

I am aware that colored enamel, consisting of two or more coats, hasbeen applied to steel. 5 5 This is accomplished by burning the firstcoat, which is usually colored with cobalt or manganese, into the steelunder excessive heat.

If any of the defects to which I have heretofore referred are present inthis first coat, they are cured or covered by the second coat of softand easyfusing glaze, which is generally opaque, so as to hide the firstcoat.

I will now describe my invention, and, in the beginning, desire to beunderstood as not limiting myself to the exact ingredients herein named,the proportion of such ingredients as I have found by experimentdesirable to use, nor the particular manner herein described of usingthe ingredients, as it is obvious that there are many equivalents whichcould be employed with more or less success.

To begin with, in the manufacture of mottled enameled ware having steelfor its base, the same general steps are employed to convert the rawmaterial into a finished article, with such exceptions as I will note,as are employed in making mottled enameled ware with iron for its base.The base, either steel or iron,having been rolled into sheets,is stampedor seamed into form and enameled.

This invention is based upon the discovery that saltpeter introducedinto the annealingpot will vaporize at a low temperature and generategases, which, attacking the surface of the metal, will cleanse it, atthe same time slightly etching said surface, rendering the metalsensitive to a superior glaze of enamel.

Saltpeter may be used alone in the annealing-pot in about theproportions hereinafter 0 stated, or it may be used in conjunction withchlorid of calcium or some other chlorid or salt with satisfactoryresults. Instead of chlorid of calcium other chlorids, a salt ofammonia, or analogous salt may be used with 5 the saltpeter and goodresults produced. Hence this invention, which, broadly considered,consists in placing saltpeter in the annealing-pot by itselfor withother ingredients named, so that a gas or gases will be generloo ated inthe annealing-pot, in the presence of which the metal base will beannealed, will not be avoided by so changing the ingredients or theproportions thereof that their equivalents will accomplish the sameresult.

In practicing this present invention the saltpeter is placed in theannealing-pot with the metal to be annealed, preferably in about theproportion of two pounds of saltpeter to one hundred pounds of steel,and the pot then exposed to the ordinary annealing-heat for about threeto six hours. I prefer to so treat the steel in what is known as thefirst annealing, that is, before the metal is shaped into vessels bystamping or otherwise, but instead of practicing my invention in thisfirst annealing it may be used with equal success after the metal hasbeen shaped, after which the metal ware thus treated can be enameledwith beneficial results, wherein the pinholes will not be present andthe flocking or chipping willbe reduced. It will be further found thatthe enamel will have a close adhesion to the metal base, which therebymakes a superior article of enameled ware.

If chlorid of calcium or any of the other ingredients named are used inconjunction with the saltpeter in the annealing-pot, I have found thatabout three-quarters of a pound of such ingredients in addition to thetwo pounds of saltpeter to one hundred pounds of metal will producesatisfactory results.

Having thus described my invention, what I claim, and desire to secureby United States Letters Patent, is-

1. The herein-described process of preparing steel for enameling, whichconsists in placing the steel and saltpeter in the annealing-pot andsubjecting the same to an ordinary annealing-heat; substantially asdescribed.

2. The herein-described process of preparing steel for enameling, whichconsists in placing the steel, a chlorid and saltpeter in theannealing-pot and subjecting the same to an ordinary annealing-heat;substantiall y as described.

3. The herein-described process of making enameled ware, which consistsin placing the metal base in an annealing-pot, placing saltpeter in saidpot with the base, applying the annealing-heat, and then applying theenamel to the base and fusing the same thereon; substantially asdescribed.

l. The herein-described process of making enameled ware, which consistsin placing the metal base in an annealing-pot, placing a chlorid andsaltpeter in said pot with the base in about the proportions set forth,applying the annealing-heat, and then enameling the base; substantiallyas described.

In testimony whereof I hereunto ai'iix my signature, in presence of twowitnesses, this lath day of March, 1896.

ALEXANDER NIEDRlNGI-IAUS.

\Vitnesscs:

HUGH K. WAGNER, F. R. CORNWALL.

